Children learn language from the evidence they encounter. They can acquire any language, English, Tamil, Arabic or any human language they encounter. The grammatical sentences that the children acquire are positive evidences. Explanations, corrections of wrong sequences, and ungrammatical sentences are negative evidences. The universal grammar theory claims that evidence other than positive evidence cannot play a critical role. That is, the child must learn mainly from positive examples of what people actually say.
Children acquire their first language despite wide differences in their situations within single culture or across different cultures. Children attain same grammatical competence although the inputs they get vary from one child to another. The knowledge of language the children get clearly reflects their experience. Children imitate what they actually hear. Imitation provides positive evidence. But imitation is not the only means by which a child learns. Correction also makes a child learns from its mistakes. That is, when the child makes mistakes his parents correct them. This way a child acquire knowledge to some extent.